1. Field of the Invention
This invention relates generally to a selective photoresponsive sensing circuit and, more particularly, to a multi-photosensor arrangement for providing a select exposure influencing control signal in a photographic camera apparatus.
2. Description of the Prior Art
Various types of single cell and multicell photosensor arrangements for photographic cameras have been developed to measure the light reflected from a scene to be photographed and provide an exposure influencing control signal which may operate to control such exposure influencing events as the duration of the film exposure interval or the flash fire time and duration for a quench strobe. The simplest photosensors for cameras generally include a single photoresponsive cell that has a field of view approximately the same as that of the camera. Various types of multicell photometers have been developed in an effort to increase the accuracy of the film exposure interval determination over a wide range of differing scene illumination conditions. In some of these multicell photometers, the individual cells are arranged in an ordered array of rows and columns occupying an overall field of view equivalent to that of the camera. The output signals from the individual photosensors are utilized to determine an exposure interval in accordance with some selected algorithm. Difficulty may arise when one of the photocells senses either an inordinately bright spot occupying a relatively small area of the scene such as a small bright lamp in the foreground portion of an interior scene or the sun in an outdoor scene thereby providing an undue influence upon the determination of the exposure interval. Such a bright spot may result in the exposure interval being shorter than what would otherwise be required to provide a full exposure of the major portion of the scene excluding the bright spot. Conversely, a dark spot occupying a relatively small area of the scene such as may result from a small, highly non-reflective object in the scene can result in a longer exposure interval than would otherwise be necessary to adequately expose the major non-dark portion of the scene. Thus, multiple photosensor arrangements may be adversely effected from either bright or dark spots which occupy relatively small portions of the scene.
Therefore, it is a primary object of this invention to provide a multi-photosensor arrangement for a photographic camera which is not adversely effected from bright or dark spots which occupy a relatively small portion of the scene to be photographed.
It is a further object of this invention to provide a multi-photosensor arrangement for a photographic camera in which the output signal from the photosensor which detects the brightest scene light and the output sensor from the photosensor which detects the lowest scene light intensity are automatically discounted so as not to adversely effect the film exposure.
It is an even further object of this invention to provide a multi-photosensor arrangement for a photographic camera which provides an exposure influencing control signal based on an average of the intermediate values of the scene light intensity sensed by the individual photosensors regardless of the highest and lowest values of scene light intensity sensed by the photosensors.
Other objects of the invention will be in part obvious and will in part appear hereinafter. The invention accordingly comprises a circuit and system possessing the construction, combination of elements and arrangement of parts which are exemplified in the following detailed disclosure.